1. Field of the Invention
The present invention relates to a transfer apparatus for transferring parts onto works with revolving end-effectors.
2. Description of the Related Art
Conventionally, there has been such an electronic parts mounting apparatus available in the field of semiconductor production for receiving chips, transferring the received chips onto works and arranging, sticking or electrically connecting the transferred chips on the works (e.g., Japanese Laid-Open Patent Publication No. H10-145091). This apparatus is a rotary type mounting apparatus having multiple transfer heads, which revolve to mount chips on works in sequence. The transfer heads are arranged coaxially around a main shaft and revolve in a circular orbit around the shaft. Operation stages are set at fixed positions on the orbit such as a suction stage where the transfer head sucks a chip from a chip feeder, and a mounting stage where the transfer head mounts the sucked chip on the work. The transfer heads stop at each of the operation stages to transfer chips. In order to keep the main shaft rotating while the transfer heads are stopping, the mounting apparatus is equipped with a fixed cam having a curve to substantially stop the transfer heads by canceling the rotational speed transmitted from the main shaft to the heads. Thus an apparatus is realized which can mount chips while its main shaft is continuously rotating.
However such apparatus for mounting electronic parts mentioned above transfers chips by means of transfer heads, the periodic motion is rigid because the motion is generated by mechanical cams. Accordingly, the transfer heads are constrained to move in conjunction with the rotation of the main shaft.
Recently, commodity control by means of disposable type RFID (radio frequency identification) tags is made in several field as a result of advancement of information technology and requirement of the laborsaving for information management. This requires mass production of cheap RFID tags (RF tags or radio tags). The mass production of RF tags may also require following processes or process technologies; feeding electronic parts for RF transmission/reception continuously at a constant pitch without halting them; receiving the fed parts without halting them; transferring the received parts without halting them onto sheet-type works having an antenna element formed on it while the works are moving continuously and are fed side by side in a constant pitch; arranging, sticking, or electrically connecting the parts onto the work. If the periodic motion of the transfer heads is rigidly fixed, following problems may occur for the mass production mentioned above. That is, it is necessary to replace the cam troublesomely for every products of a different size or pitch. Besides, because the motion of the transfer heads is limited, the heads cannot follow an irregular change of the pitch of fed parts or an irregular change of the pitch of moving works. Those transfer heads cannot respond to random pitch changes or real-time fine adjustment, and consequently, accurate parts positioning is impossible.
Another conventional transfer mechanism is known, which includes a single transfer head and has an electronic cam driven by a single motor with which period can be changed. However, the single transfer head is not adaptable for high-speed mass production even though it may ensure positioning accuracy.